1. FIELD OF THE INVENTION
The present invention relates to a method and apparatus for solder plating an object having many parallel aligned positions to be solder plated, e.g. leads of an electronic part of a QFP (Quad Flat Package IC) having leads on four sides, or a SOIC (Small Outlet IC) having leads on both sides.
2. DESCRIPTION OF THE PRIOR ART
Electronic part such as QFP or SOIC utilizes ferrous or copper alloy as lead material. However, as the IC circuit and the leads are connected by gold wires, the leads are gold plated to fit with gold wires. The gold plated lead has a poor soldering property and further, as gold easily melts into solder material to form a brittle metal to metal compound of gold and tin during the soldering process thus producing a weak soldered product. Thus, conventionally, the gold plated leads are solder plated to improve affinity to solder when the leads are connected by soldering to other electronic parts on a printed circuit board.
A conventional solder plating process of leads is performed such that for example lead wires of QFP, flux is covered on the leads and leads on one side are kept perpendicular to the molten solder liquid surface and are dipped into the molten solder and then, the QFP is turned 90.degree. to align the leads of the next side to face the molten solder. The process is repeated so that four processes must be performed to solder plate all the lead wires on one QFP.
Such a conventional solder plating process nescceciates four dipping processcs to one QFP which has leads of four sides. Further, by dipping the leads into the molten solder bath, solder apts to bridge between adjacent leads when the distance between the adjacent leads is narrow.
Accordingly, the object of the present invention is to provide a method and an apparatus of solder plating which can solder plate by one dipping process into molten solder for leads of electronic parts such as QFP which has leads on four sides without causing bridging between the adjacent leads.